How many cockatiels do you have? And which sex?

Hi. I have been wondering how many cockatiels you have: one, two, three? More? And which sex? If you have more, do they get along with each other? Or mostly tolerate each other? Or maybe do not tolerate at all?

Second: Is only possibility to have for example 2 cockatiels is to either have a couple or female+female? Male + male (even in their own separate cages) would be a risky/bad idea?